phosphorous vs phosphorus

phosphorous is not a noun while phosphorus is a noun.

Word	Noun	Adjective	Verb	Adverb
phosphorous	No	Yes	No	No
phosphorus	Yes	No	No	No

phosphorous (noun)	phosphorus (noun)
	a multivalent nonmetallic element of the nitrogen family that occurs commonly in inorganic phosphate rocks and as organic phosphates in all living cells; is highly reactive and occurs in several allotropic forms

phosphorous (adjective)	phosphorus (adjective)
containing or characteristic of phosphorus